OBJECTIVES: This study is to evaluate the relative effectiveness of cold knife conization, cryosurgery, and the CO2 laser in the treatment of preinvasive cancer of the cervix, i.e., dysplasia and carcinoma in situ. APPROACH: Patients with abnormal Pap smears will be evaluated by cyotology, colposcopy and biopsy. Those patients not at risk of having invasive cancer will be randomized to treatment by one of these three modalities. Follow-up is planned for five years post treatment.